The present invention relates generally to cooling systems. More particularly, the present invention relates to cooling systems for regulating the temperature of electronic components of electronic devices. The present invention is particularly, but not exclusively, useful for cooling systems that regulate the temperature of electronic components of blade servers.
The regulation of the temperature of electronic components like processors due to heat generated inside the housing of an electronic device like a blade server is an important consideration during the design of an electronic device. Cooling is important because if left unchecked, heat can cause electronic devices to malfunction during use or lead to premature device failure. As improvements in processor speed occur, the amount of heat generated by the faster processors also increases. Additionally, improved processors require larger power supplies and auxiliary components that generate increased amounts of heat and require improved systems for heat removal.
Another factor that aggravates the need for improved heat removal cooling systems is the trend towards making computing devices such as blade servers smaller and especially thinner. The trend toward smaller and thinner electronic devices having larger, faster processors renders the traditional heat removal cooling systems inadequate for several reasons. First, smaller devices having faster processors result in an increased density of heat producing electronic components leading to higher localized concentrations of heat. Also, a decreased amount of space is available for localized temperature regulating devices such as traditional heatsinks. Lastly, a decreased amount of space is available to create ventilation paths that pass by heat sources. Thus, traditional blower assemblies having an inlet from above the blower that ventilate the entire housing of the device are less effective or inapplicable in removing heat when used in smaller, thinner devices.
There are numerous designs of cooling systems for electronic devices that include a blower-assisted heatsink located directly at the electronic component. These conventional coolers had been using axial or radial blowers primarily. But, in spite of relatively high blower efficiency at regular size of axial and radial blowers, the blower efficiency drops dramatically when these blowers have been used for relatively small size cooling systems.
There are known devices of this type, for example, U.S. Pat. No. 6,196,300 “Heatsink”. The device described in this US patent comprises an axial fan that produces a flow passing by heat-exchanging channels of the heatsink. The majority of inlets to the heat-exchanging channels are located just opposite of the axial fan's impeller with a certain number of said channels being placed radially in relation to the fan axle.
The axial fan produces sufficient air pressure. However, due to the weak airflow in the area adjacent to the fan axle, the conditions for cooling of the central part of the heatsink located underneath a hub of the fan are unfavorable. In this case non-uniform cooling of the heatsink and electronic components will take place. It does not allow obtaining good conditions for the heat-exchange process.
Centrifugal (radial) blowers are used more rarely in cooling device designs for the purpose of producing airflow.
Specifically, U.S. Pat. No. 5,838,066 “Miniaturized cooling fan type heatsink for semiconductor device” offers a design employing a radial blower that is installed to the side of the heatsink. In one particular embodiment of this invention the cooling airflow passes by rectilinear means through the heat-exchanging channels of the heatsink.
However, placement of a centrifugal blower to the side of the heatsink increases the device size and reduces its effectiveness because the location of the radial blower leads to insufficient coordination between the direction of channel inlets and direction of airflow supplied from the blower. The loss in airflow energy results in the reduction of airflow speed in the heat-exchanging channels and the reduction of heat-exchange efficiency. A portion of airflow energy is also expended as friction against the casing that encloses the blower.
An invention described in the patent of Japan No. 8-195,456 “Cooler for electronic apparatus” comprises a radial blower enclosed in the casing and an electric drive located out of the casing. The blower is installed above the heat-exchanging channels of the heatsink. Another heatsink surface is made so that the possibility of thermal contact with an electronic device is provided for. The inlet of the radial blower faces the heatsink. The radial blower produces an airflow that passes by the heat-exchanging channels and then gets drawn into the inlet of said blower. Such electric drive placement visibly increases the thickness of the cooling device as a whole.
Thus, the main problem arises when using the radial blower assisted heatsink—on the one hand the placing of the electric drive inside the impeller of the blower leads to sufficient decreasing of the blower and thermal efficiency, and on other hand, placing of the electric drive outside of the blower impeller leads to sufficient increasing in size.
Therefore, it would be generally desirable to provide an apparatus that overcomes this problem associated with a cooler comprising a radial blower assisted heatsink and has a relatively high blower and thermal efficiency without the need to increase the volume and even with smaller volume, especially with a lesser thickness of the cooler.